Festivalen ble arrangert fra 01 Sep til 18 Sep 2021 (17 dag(er)).
Summerfest finner sted i Milwaukee, United States. Her er den fullstendige adressen til festivalen: Henry Maier Festival Park; Milwaukee, Wisconsin, United States
Green Day, Chris Stapleton, Jonas Brothers, twenty one pilots, Zac Brown Band, Fall Out Boy, Dropkick Murphys, Luke Bryan, Weezer, Falling in Reverse, Mother Mother, Miley Cyrus, Styx, Rise Against, Wiz Khalifa, Lindsey Stirling, ZZ Top, REO Speedwagon, Nelly, Dave Matthews Band, Blackberry Smoke, SpiritBox, 311, Ani DiFranco, Polo G.
De mest populære sjangrene og undersjangrene i den siste utgaven var:
rock
pop
hip hop
alternative
alternative rock
indie
hard rock
indie rock
pop rock
classic rock
rnb
indie pop
emo
metal
punk rock
acoustic
blues rock
grunge
new wave